I've spent the last few hours trying to make sure I understood your explanation of decoupling capacitors.
Here's what I've come up with:
- in the "Name that thing" category (where naming is used to translate from some electronic activity to something easily understandable..but ultimately named based on history and/or a engineer's context…) a decoupling capacitor is 50% a good name. Why 50%? because a capacitor said to be decoupling can be tasked to do one or both of these jobs: 1) filter out high frequency noise (for this slather a .1uF capacitor - see figure 2 in this document: http://www.analog.com/static/imported-f ... MT-101.pdf
). This is the decoupling aspect. Seems similar to me trying to filter out "NO YOU CAN'T" throughout my life… 2) provide charge when a component switches because the charge needed by the component come in bursts and the available charge might not have enough oomph.
-----(WARNING: a conversational divergent you might wish to ignore)
The conversation above gives a great explanation of an IC using a capacitor as a gas station (can you tell I took home economics in school way back when but also worked at a gas station until some kids almost tore off my arm - i had to pump all cars at that point. Don't get me started about guys in the cadillac handing me a $1 and keeping their car running while their gas nozzle thingy was located strategically close to the yuck be emitted…but I diverge…sorry…).
So then, I want to make sure the RFM69HW gets the energy it needs while filtering out the bad noise so that the circuit, the chip - heck our collective lives in learning!!! are the best they can be.
What capacitors should I put near the RFM69HW AND IN PARALLEL? :-)
1) a .1uF capacitor to filter out the high frequency noise (I'll refer to this as WHAT? OUCH TURN THAT SOUND OFF)
2) a 10uF capacitor to provide some of the charge/voltage the RFM69HW can use when it uses 130mA of current to transmit data. I pick this value because it seems many schematics use it…however…i am not clear if I were calculating the total amount needed to handle 130mA. Is using C=Q/V OK in this scenario? In that case C = 0.13A/3.3V = 0.04F … which seems large to me…which means I don't have an understanding of calculating the size of capacitor to use based on current used by the IC when the IC asks for a bump of current at high speeds…
I was looking at docs that explained this and perhaps if I spent more hours reading them slowly lights will dawn. I was hoping you could explain this far easier? Dunno...
Thank you again. How amazing it is to learn and apply this stuff!